Development of the NS Flashcards
during brain development how many neurons are added every minute
250,000
at birth how may neuros are present
almost all the neurons that the brain will ever have
when does the brain grow
continues to grow for a few years after birth
when is the brain 80% of the adult size
age 2
what do glia do
continue to divide and multiply
1st indication of the future nervous system
neuroectoderm
contains the neural plate
when does neuroectoderm occur
16th day after fertilization
week 3
where does the neural plate appear
dorsal midline of the embryo
what do the cells of the neuro plate do
become taller than those of the ordinary ectoderm
–> underlying mesodermal cells
how do the cells of the neural plate grow
rapidly
–> in 2 days becomes a neural groove with a nerual fold along each side
what do the neural fold and groove give rise to
neural tube
development of neural tube
neural plate –> neural groove –> neural tube
process of the development of the neural tube
neurulation
where does the closure of the neural groove occur
midcervical level
where does the closure of the neural groove continue
caudal and cranial directions
when does the neural tube form
3rd week
stage 10
what is the neural tube the forerunner of
brain and spinal cord rostrally and caudally
neuropores –> neural tube
rostral and caudal
rostral neuropores
close at day 25
failure of rostral neuropore closure
anencephaly
caudal neuropores
close at day 27
failure of caudal neuropores to close
spina bifida
neuro-epithelium –> neural tube
cells lining the tube from which neurons and other cells arise
neural crest
neuroectodermal cells that are not incorporated in the tube
nonneural cells (neuroglia) of peripheral nerves
where is the neural crest
dorsal root ganglia of spinal nerves
example of a nonneural cell (neuroglia)
schwann cell
placodes
thickened regions of the ectoderm of the head’s structure
what do placodes do
give rise to some peripheral nervous elements –> sense organs
